A throw-down with a prehistoric terror in the heart of Washington D.C. sets the stage for the dramatic return of a wayward hero! Meanwhile, half a world away, a sinister plan begins to awaken an ancient evil! PLUS: Riverdale High’s new substitute teacher is very odd. Snubbed by the scientific community, he plans his revenge – on the students of Riverdale High! It’s going to take a team of people with some mighty powers to stop him.